粤西北地区岩溶水系统结构特征研究

he structural characteristics of the karst aquifer system are critical for groundwater storage and contaminant transport. However, research on the karst regions in northwest Guangdong remains limited. This study investigates a typical underground river system in Qingyuan, Guangdong, using various technical methods to explore the structural features of the karst aquifer system. The results show that the Qingyuan karst aquifer is primarily composed of Carboniferous and Devonian limestone, with a permeability coefficient as high as 22 m/d. The system responds rapidly to rainfall, with peak flow rates initially dominated by rapid flow through conduits, followed by slow flow through fractures, typical of a conduit-fracture hydrological system. Field tracer tests reveal that the Carboniferous karst system has a single-source, multi-sink structure, whereas the Devonian system contains multiple flow paths and large underground dissolution ponds. Additionally, the karst conduits show significant topographic variation, with average diameters of 1.29 m and 7.53 m for the Carboniferous and Devonian formations, respectively, and dispersion coefficients between 2.3 and 6.4 m2/s. These findings indicate that the karst groundwater system is highly vulnerable. This study offers theoretical support for the development and protection of karst water resources in northwest Guangdong.